The present invention relates to an apparatus for helping to protect a vehicle occupant in the event of a vehicle collision, and particularly relates to an inflator for providing inflation fluid for inflating an inflatable vehicle occupant protection device.
An inflator that provides inflation fluid to inflate an inflatable vehicle occupant protection device is known. In certain inflators, the inflation fluid is generated by ignition of a gas generating material in the inflator.
Some gas generating materials are azide based, while other gas generating materials are non-azide based. A non-azide based gas generating material typically supplies a higher yield of gas (moles of gas per gram of gas generant) than an azide based gas generating material. A non-azide based gas generating material, however, can produce inflation fluid with a temperature above 700xc2x0 C. and with higher levels of carbon monoxide (CO) and nitrogen oxides (NOx) than azide based gas generating material. It is desirable to reduce the levels of carbon monoxide (CO) and nitrogen oxides (NOx) in the inflation fluid produced by a non-azide based gas generating material before the inflation fluid flows into the air bag.
The present invention is an apparatus for helping to protect a vehicle occupant. The apparatus comprises an inflatable vehicle occupant protection device and an inflator for providing inflation fluid to inflate the vehicle occupant protection device. A non-azide gas generating material is in the inflator. The non-azide gas generating material, when combusted, produces inflation fluid that comprises carbon monoxide (CO) and nitrogen oxides (NOx) . A filter assembly that contacts the inflation fluid is in the inflator. The filter assembly comprises a catalyst system and an oxygen gas generating material. The catalyst system is reactive with the carbon monoxide (CO) and nitrogen oxides (NOx) to lower the concentration of carbon monoxide (CO) and nitrogen oxides (NOx) in the inflation fluid. The catalyst system comprises a zeolite and a catalytic material.